The present invention relates to an earth-working machine such as an excavator for digging ditches in road construction.
As shown in FIG. 1 of the accompanying drawings, a known excavator 1 for trenching a ditch in and along one lane of a road is placed on that lane, blocking off the traffic on the lane while allowing the traffic on the other lane. In operation, a bucket arm 2 of the excavator 1 is moved up and down to cause a bucket 3 on the bucket arm 2 to dig a trench 4 in and along the road lane. The material scooped by the bucket 3 is then dumped onto a loading platform 6 of a truck 5 positioned behind the excavator 1. As the trench 4 is digged on successively, the excavator 1 is required to move back in the direction of the arrow Z so as to be prevented from falling off into the trench 4 which has just been digged. For tranferring the digged material from the trench 4 over to the loading platform 6, it is necessary to turn the bucket 3 and hence the bucket arm 2 along a semicircular path Y about a center X of the excavator 1. Since the path Y of the bucket 3 extends into the other lane, the traffic on the other lane must be either stopped totally or interrupted only when the bucket arm 2 is to swing over for preventing any unwanted accident. However, such entire or temporary traffic interruption is bound to cause a traffic jam while the road is under construction. Furthermore, the large radius of swinging movement of the bucket arm 2 suffers from the danger of the bucket 3 to hitting and injuring careless people who may walk into the range of turning movement of the bucket arm 2.